The value of a cotton crop is determined by a combination of yield and quality parameters. Research to date has concentrated on the yield side of this relation. The objective here was to determine the relations between physiological and AFIS maturity/quality parameters and various environmental inputs. Two cotton varieties were grown in 1992 (PIMA S-6, DES 119) and two in 1993 (DPL 5415, PIMA S-6) in Starkville, MS. Cotton bolls were harvested at selected times throughout the growing season and analyzed by AFIS and Calcium-XRF techniques. Temperature data, at daily increments, was used to calculate heat accumulation (growing degree days) by several methods. Although several base and ceiling temperature combinations were investigated, the analyses indicated that a ceiling temperature of 32 oC combined with a base temperature of 13.5 oC consistently resulted in the highest correlations with fiber properties. For this reason, only data for these temperatures are presented.